1. Field of the Invention
The present invention relates to an insert material embedded in an air bag cover including an unfolding portion which is unfolded by a bag body swelling toward a driver when a vehicle is rapidly decelerated.
2. Background Information
In an air bag apparatus, for example, in an air bag apparatus of a type which is mounted on a steering wheel, a circular hole 100 is formed in an intermediate portion of a substantially box-shaped base plate 102 as shown in FIG. 7. An unillustrated inflator is arranged in the circular hole 100 of the base plate 102 to emit gas when a vehicle is rapidly decelerated. A substantially frame-shaped insert plate 104 is fitted with the base plate 102, and they are connected with each other by an unillustrated bolt or the like. The insert plate 104 is embedded in an air bag cover 106 (see FIG. 6) by insert molding. The insert plate 104 is provided with a rectangular frame-shaped base portion 104A, a pair of mesh materials 104B and 104C embedded in unfolding portions 106A and 106B of the air bag cover 106 as will be described below, and coupling portions 104D and 104E coupling the base portion 104A with the mesh materials 104B and 104C. The mesh materials 104B and 104C serve to prevent the unfolding portions 106A, 106B of the air bag cover 106 from scattering. The unfolding portions 106A, 106B of the air bag cover 106 are unfolded by an unillustrated bag body swelling toward a driver.
However, as shown in FIG. 6, if the above-mentioned air bag cover 106 is unfolded when the vehicle is rapidly decelerated, the coupling portions 104D and 104E (which are also shown in FIG. 6) coupling the mesh materials 104A, 104B with the insert plate 104 are defined as center positions about which the air bag cover 106 unfolds. Accordingly, a substantial opening width at a time when the bag body is swelled becomes narrow and is equal to a distance P between inner surfaces of the unfolding portions 106A and 106B of the air bag cover 106. Therefore, in conventional air bag apparatus, nain cloth forming the bag body has high strength so that the bag body swelling out of the opening having the narrow width is not damaged. As a result, there are some drawbacks such as the bag body being manufactured at a high cost.
In order to overcome the drawbacks, as shown in FIG. 5, an air bag cover 110 may be made large so as to provide an opening width Q larger than the opening width P at a time when the respective unfolding portions 110A and 110B unfold. However, if the air bag cover 110 itself is enlarged, there is another drawback in that degree of freedom in designing the air bag cover 110 is reduced.